

A373575


Numbers k such that k and k1 both have at least two distinct prime factors. First element of the nth maximal antirun of nonprimepowers.


14



1, 15, 21, 22, 34, 35, 36, 39, 40, 45, 46, 51, 52, 55, 56, 57, 58, 63, 66, 69, 70, 75, 76, 77, 78, 85, 86, 87, 88, 91, 92, 93, 94, 95, 96, 99, 100, 105, 106, 111, 112, 115, 116, 117, 118, 119, 120, 123, 124, 130, 133, 134, 135, 136, 141, 142, 143, 144, 145
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OFFSET

1,2


COMMENTS

The last element of the same antirun is given by A255346.
An antirun of a sequence (in this case A361102) is an interval of positions at which consecutive terms differ by more than one.


LINKS



EXAMPLE

The maximal antiruns of nonprimepowers begin:
1 6 10 12 14
15 18 20
21
22 24 26 28 30 33
34
35
36 38
39
40 42 44
45
46 48 50


MATHEMATICA

Select[Range[100], !PrimePowerQ[#]&&!PrimePowerQ[#1]&]


CROSSREFS

Runs of primepowers:
Runs of nonprimepowers:
Antiruns of primepowers:
Antiruns of nonprimepowers:
A057820 gives first differences of consecutive primepowers, gaps A093555.
A356068 counts nonprimepowers up to n.


KEYWORD

nonn


AUTHOR



STATUS

approved



